1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus, and more particularly, to a developing device removably mounted in a main body of the image forming apparatus, and an image forming apparatus having the developing device.
2. Description of the Related Art
An image forming apparatus, such as a printer, a copying machine, or a fax machine, forms an image on a printing medium according to an inputted image signal. Of the various types of image forming apparatuses, an electrophotographic image forming apparatus prints an image on the printing medium, such as paper, through feeding, developing, transferring, fusing, and discharging processes.
An image forming apparatus generally includes a cartridge type developing device in which a photosensitive body, a charging body and a developing body are integrally formed as a unit. The developing device is removably mounted in a main body of the image forming apparatus.
For the developing device to operate reliably and develop an image of high quality, the developing device should be stably mounted in a correct position in the main body. In addition, to provide a user with convenience in replacing the developing device or inspecting the interior of the image forming apparatus, the developing device should be mounted in the main body to be easily removable.
U.S. Pat. No. 5,937,240 discloses a developing device of an image forming apparatus, which can be mounted and removed to and from a main body only by pushing and pulling a knob of the developing device.
The disclosed developing device of U.S. Pat. No. 5,937,240 includes a first protrusion and a second protrusion which are formed on a side surface. The first protrusion determines a mounting position of the developing device. The second protrusion is positioned in a rear of the first protrusion with respect to a mounting direction of the developing device. The second protrusion maintains a posture of the developing device, and serves as a rotational center when the developing device is removed from the main body. The main body of the image forming apparatus is formed with a guide groove to guide the first protrusion and the second protrusion. The guide groove is formed with a positioning recess at a lower end thereof.
The disclosed developing device of U.S. Pat. No. 5,937,240 further includes a photosensitive body gear mounted to an end of a photosensitive body. When the developing device is mounted in the main body of the image forming apparatus, the photosensitive body gear is engaged with a driving gear mounted in the main body.
The operation of mounting and removing the developing device to and from the main body of the image forming apparatus will now be explained briefly. First, the first protrusion of the developing device is fitted into the guide groove of the main body, and the developing device is pushed in. The first protrusion and the second protrusion are guided by the guide groove. When the first protrusion is received in the positioning recess, the mounting of the developing device is completed. At this time, the photosensitive body gear is engaged with the driving gear.
When a user pulls the developing device from the main body, the developing device is rotated about the second protrusion. The first protrusion and the photosensitive body gear move upward, and are separated from the positioning recess and the driving gear, respectively. In such a state, when a user pulls even more on the developing device, the first protrusion and the second protrusion are guided by the guide groove, and the developing device is removed from the main body.
However, when the above described developing device of U.S. Pat. No. 5,937,240 rotates on the second protrusion, the moving range of the developing device is large. Thus, the above described developing device requires a large surrounding space for movement. Especially, a portion of the developing device which is spaced farthest from the second protrusion (i.e., a portion having the largest moving range) is positioned in a substantially center portion in the main body of the image forming apparatus. However, many other components are arranged densely in the center portion in the main body. Thus, a size of the image forming apparatus is increased to provide sufficient space for movement of the developing device in the center portion in the main body, which makes it difficult to compactly manufacture the image forming apparatus.
After the developing device is mounted in the main body of the image forming apparatus, when the driving gear is rotated by a driving source mounted in the main body, a rotational force is transmitted to the photosensitive body through the photosensitive body gear. In such a power transmission process, the developing device may vibrate. In order to restrain the vibration of the developing device, a press device may also be provided in the main body to press the developing device downward.
However, when the developing device disclosed in U.S. Pat. No. 5,937,240 is removed from the main body, the developing device is rotated largely in a direction opposite to the direction of a pressing force of the press device. In other words, while the pressing force of the press device acts downward, a portion of the developing device is rotated upward to be removed from the main body. Thus, when intending to remove the developing device from the main body of the image forming apparatus, a user should apply a force to the developing device that is larger than the pressing force of the press device. However, to aid the removal of the developing device from the main body, if the pressing force of the press device is set to be relatively lower in consideration of handling convenience, stably restraining the vibration of the developing device becomes more difficult. Conversely, if the pressing force of the press device is set to be relatively higher, handling convenience is deteriorated as removal of the developing device from the main body becomes more difficult.
The developing device is mounted with components (for example, terminals) on an upper surface thereof, which are contacted with components mounted in the main body when the developing device is installed in the main body. However, when the developing device is rotated upward in order to be removed from the main body, the components mounted on the upper surface of the developing device may be damaged by forced contact with the components mounted in the main body.